Preheat oven to 350°F. Mash peanut butter cups with a food processor until a smooth paste is formed. Add in 1/2 of an egg and baking soda and mix until batter is smooth.
Take 2 tbsp dough and roll between palms until smooth balled is formed. Place onto baking sheet lined with parchment paper. Repeat with remaining dough, spacing 2 inches apart.
Bake for 10 minutes. Cookies will initially be puffy, but will sink down when cooled. Let the cookies cool on the cookie sheet until flattened before removing.
The nutrition information provided are only estimates based on an online nutritional calculator. This is not a comprehensive list of all the nutrients in the recipe (i.e., does not include vitamins, cholesterol, etc). I am not a certified nutritionist. Please consult a nutritionist or doctor for accurate information and any dietary restrictions and concerns you may have.